<!DOCTYPE html>
<html lang="en">
  <head>
    <title>a</title>
    <style>
      .units{
        display: flex;
      }
      .sua{
        background-color: blue;
        width: 100px;
        height: 100px;
      }
      .sub{
        background-color: red;
        width: 100px;
        height: 100px;        
      }
      .bu{
        
      }
    </style>
  </head>
  <body>
    <div>
      <div>
        <div class="units">
          <div>
            <div class="units">
              <div class="sua">a</div>
              <div class="sub">b</div>
            </div>
            <div class="units">
              <div class="sub">b</div>
              <div class="sua">a</div>
            </div>
          </div>
          <div>c</div>
        </div>
      </div>
      <div>
        <div class="units">
          <div>
            <div class="units">
              <div>a</div>
              <div>b</div>
            </div>
            <div class="units">
              <div>a</div>
              <div>b</div>
            </div>
          </div>
          <div>c</div>
        </div>
      </div>
    </div>
  </body>
</html>